There is an urgent need for new antivirals for both treatment and control of dengue virus, given that over 50 million people are infected worldwide with dengue every year, including 500,000 cases of the more severe form of the disease, dengue hemorrhagic fever (DHF) and there are no approved vaccines or antiviral drugs available. Vaccine development is promising but faces several significant challenges including the need to balance protection against all four serotypes of the virus equally in order to avoid antibody-dependent enhancement of infection and risk of DHF. An antiviral drug that inhibits viral replication without increasing the risk for ADE would be extremely valuable for both public health by providing a means to control outbreaks, as well as to government stockpiles for biodefense preparedness. The overall goal of the SIGA dengue program is to develop a small molecule therapeutic for the treatment and/or prevention of disease caused by dengue virus. A sensitive and specific high throughput screening (HTS) assay has been developed to evaluate compounds from the SIGA chemical compound library for inhibitory activity against dengue-2 (DEN-2) virus replication. Hits have been identified that are potent (EC50<5uM) and selective (CC50>25uM), with initial structure activity relationship in several series of related compounds. Lead series will be defined by spectrum of activity, mechanism of action, preliminary absorption, distribution, metabolism, and excretion (ADME) profiles, and pharmacokinetic (PK) evaluations. Based upon the outcome of the biological characterizations, chemical tractability of related analogs, cheminformatic analyses, and nascent structure activity relationships, one or two lead compound series will be selected for chemical optimization to generate a preclinical candidate. PUBLIC HEALTH RELEVANCE: The overall goal of the SIGA dengue program is to develop a small molecule therapeutic for the treatment and/or prevention of disease caused by dengue virus. . [unreadable] [unreadable] [unreadable]